Common methods for conveying solid materials include bucket elevators, scraper conveyors, pneumatic conveying systems, belt conveyors, screw conveyors, and roller conveyors. These systems use different conveying principles and vary in their suitability for different materials, conveying distances, lifting heights, and throughput requirements.
In industrial applications, solid materials can generally be divided into bulk materials and individual items. Powders, granules, sand, and small lumps are commonly handled by bucket elevators, scraper conveyors, pneumatic conveying systems, or screw conveyors. Cartons, pallets, packages, and mechanical components are more commonly transported by belt conveyors, O-ring belt-driven roller conveyors, and chain conveyors.
The appropriate conveying method depends on the material properties, route, required throughput, available installation space, and production process.
Bucket Elevators
A bucket elevator is a mechanical conveying system that uses circulating buckets to lift material vertically. The buckets are attached to an endless belt or chain. During operation, they collect material at the bottom of the elevator, travel upward inside the casing, and discharge the material at the top by centrifugal force, gravity, or another discharge arrangement.
Bucket elevators are mainly used for vertically conveying powders, granules, and small bulk materials. Common applications include grain processing, animal feed, food production, mining, building materials, chemical processing, and metallurgy.
Main features:
Suitable for vertical lifting: The upright structure allows material to be raised to elevated hoppers or processing equipment while occupying relatively little floor space.
Continuous conveying: The buckets circulate continuously, providing a steady material flow for different production requirements.
Enclosed conveying path: The buckets generally operate inside an elevator casing, helping reduce material spillage and dust release.
Different drive configurations: Depending on the load and material properties, the elevator can use a belt, round link chain, or plate chain, with buckets selected to suit the application.
Bucket elevators are primarily designed for vertical conveying and have limited horizontal conveying capability. They are generally used with other conveying equipment when horizontal material transfer is required. For fragile, sticky, or highly abrasive materials, bucket design, operating speed, traction elements, and contact surface materials need to be considered.
The actual lifting height and throughput depend on the equipment model, material bulk density, bucket capacity, operating speed, and drive power. A single lifting height should not be used as a general limit for all bucket elevators.
Scraper Conveyors
A scraper conveyor uses a chain to move scrapers through a trough. The scrapers push material along the conveying channel. Depending on the equipment design and installation arrangement, scraper conveyors can handle horizontal or inclined conveying. Some specialized configurations are also designed for steeper lifting applications.
Scraper conveyors are commonly used for coal, grain, animal feed, powders, granules, and small bulk materials. Applications include mining, grain processing, building materials, chemical processing, and power generation.
Main features:
Compact structure: The chain, scrapers, and conveying trough form the main conveying mechanism, allowing material transfer within a relatively small installation space.
Good dust containment: An enclosed trough can reduce dust release and material spillage, making it suitable for applications with environmental control requirements.
Flexible feed and discharge arrangements: Some models can be configured with multiple feed and discharge points to connect different process equipment.
Continuous conveying: The chain drives the scrapers in a continuous cycle, moving material along the trough.
The conveying capacity and allowable inclination depend on the chain configuration, scraper design, trough dimensions, and material properties. As the inclination increases, material may slide backward, reducing conveying capacity. Equipment structure and operating parameters must account for this effect.
The chain and scrapers are in continuous contact with the material and may experience abrasive wear. Sticky or agglomerating materials can also cause buildup inside the trough and increase cleaning requirements.
Pneumatic Conveying Systems
Pneumatic conveying uses the kinetic energy of airflow or a pressure difference to move solid materials through enclosed pipelines. A typical system consists of a fan or compressed air source, feeding equipment, conveying pipelines, separation equipment, and dust collection devices.
Depending on the pressure conditions and airflow direction, pneumatic conveying systems can be classified as positive-pressure or vacuum conveying systems. They can also be divided into dilute-phase and dense-phase conveying according to the material flow pattern inside the pipeline.
In dilute-phase conveying, particles are suspended and carried by relatively high-velocity airflow. In dense-phase conveying, material moves at a lower air velocity and higher solids concentration, often in the form of plugs or compacted sections.
Main features:
Flexible pipeline layout: Pipelines can be arranged horizontally, vertically, or at an inclination to suit the factory layout and production line.
Enclosed material handling: Material moves inside the pipeline, helping control dust release. This is useful for certain bulk material handling applications in the food, chemical, plastics, pharmaceutical, and building materials industries.
High automation potential: The system can be integrated with hoppers, feeders, separators, and control equipment for automatic material transfer and distribution.
Flexible distribution: Pipelines, valves, and diverter devices can be combined to deliver material to different receiving points.
Pneumatic conveying also has limitations. Fans and compressed air equipment consume energy, and poor system design or operating conditions can increase power consumption. High air velocity may cause particle breakage and accelerate wear at pipe bends and along the inner pipe walls.
Materials with high moisture content, strong adhesion, or a tendency to form lumps may cause pipeline blockages. For combustible or explosive dusts, the system requires suitable protection based on the material hazard assessment. This may include grounding, explosion venting, and explosion isolation measures.
There is no universal maximum particle size of 30 mm for pneumatic conveying. The applicable particle size depends on material density, shape, flowability, conveying velocity, pipe diameter, and system pressure. For large lump materials, mechanical conveying methods are generally more suitable.
O-Ring Belt-Driven Roller Conveyors
An O-ring belt-driven roller conveyor uses round-section elastic belts to transmit power to conveyor rollers. Friction between the rollers and the conveyed items moves cartons, totes, pallets, and other individual loads along the conveyor.
The O-ring belts are generally installed beneath the rollers and transmit power from a drive shaft to the rollers. Depending on the load requirements and drive arrangement, the system can use a single or double O-ring belt configuration.
Main features:
Smooth operation: The round belts drive the rollers and provide a suitable conveying method for light-duty applications where stable movement and relatively low noise are required.
Modular construction: Rollers, belts, and support frames can be combined according to the required conveyor length and width, making layout adjustments and maintenance relatively straightforward.
Convenient belt replacement: Worn or aged O-ring belts can be replaced according to the conveyor drive arrangement.
Suitable for individual loads: Common applications include cartons, plastic totes, pallets, and mechanical components used in conveying and accumulation systems.
O-ring belt-driven roller conveyors are mainly designed for individual items. They are not suitable for directly transporting loose powders, granules, sand, or other bulk materials. Load capacity also depends on roller spacing, belt specifications, drive configuration, and the bottom structure of the conveyed item.
These conveyors are commonly used in packaging, food processing, pharmaceutical production, electronics manufacturing, and logistics sorting systems.
Belt Conveyors
A belt conveyor uses a drive pulley to move an endless conveyor belt, carrying material from the loading point to the discharge point. A typical system consists of a conveyor belt, drive unit, pulleys, idlers, tensioning device, and supporting frame.
Depending on the structure and installation arrangement, belt conveyors can be fixed, mobile, inclined, or designed for specific applications. The belt material may include rubber, PVC, PU, or other materials suited to the conveyed material and operating conditions.
Main features:
Suitable for long-distance conveying: Belt conveyors can transport materials continuously over relatively long distances. Multiple units can be connected to form a complete conveying line.
High conveying capacity: Belt width, belt speed, and trough configuration can be selected to meet different material and throughput requirements.
Wide material compatibility: They can handle powders, granules, and bulk materials, as well as cartons, packages, and other individual items.
Relatively smooth conveying: The continuous contact between the belt and material helps limit impact during transport.
Established maintenance procedures: Routine inspection focuses on the belt, pulleys, idlers, tensioning device, and drive system.
The allowable inclination of a belt conveyor depends on the material's angle of repose, friction coefficient against the belt surface, belt speed, and belt design. A standard flat belt is not suitable for every steep-angle application. Cleated belts, chevron belts, or other anti-slip designs may be required.
Open belt surfaces can also release dust or allow spillage when conveying dusty materials. Depending on site requirements, covers, loading chutes, or dust collection systems may be needed.
A chain conveyor should be distinguished from a belt conveyor. A belt conveyor uses a continuous belt to carry material, while a chain conveyor uses chains and their attachments to support or move loads. A system that uses chains and scrapers to push bulk material through a trough is generally classified as a scraper or drag conveyor.
Screw Conveyors
A screw conveyor, also known as an auger conveyor, uses a motor and gearbox to rotate a screw shaft. The helical flight pushes material along a trough or tube.
Common designs include shafted and shaftless screw conveyors. Depending on the material and available installation space, the equipment may use a tubular casing, U-shaped trough, or a specially designed vertical screw arrangement.
Screw conveyors are mainly used for horizontal or inclined conveying of powders, granules, and some small bulk materials. Common applications include food processing, animal feed, plastics, chemical processing, building materials, and environmental engineering.
Main features:
Compact structure: The main components include a screw shaft, helical flight, trough or tube, and drive unit. This allows flexible equipment arrangement in many production facilities.
Good containment: Tubular or enclosed trough designs help reduce dust release and material spillage.
Suitable for controlled feeding: Material flow can be adjusted by changing the screw speed and design parameters. Screw conveyors are commonly used for feeding and batching operations.
Flexible feed and discharge arrangements: Some designs can have multiple feed or discharge points and connect with hoppers, mixing equipment, and other conveying systems.
Screw conveyors also have limitations. The screw flight remains in contact with the material during operation and is subject to wear. The conveying action may also apply compression or shear to the material, making some designs unsuitable for fragile products.
For highly abrasive materials, wear-resistant flights and troughs may be required. Sticky or agglomerating materials can adhere to the screw and casing, leading to material buildup and reduced conveying efficiency.
Standard screw conveyors are mainly designed for horizontal or slightly inclined conveying. As the inclination increases, material rollback may become more significant and conveying capacity may decrease. Vertical conveying requires a specially designed vertical screw conveyor. A standard horizontal screw conveyor should not be used for substantial vertical lifting without confirming its suitability.
Chain Conveyors
A chain conveyor uses one or more continuously moving chains to transport items or materials. Depending on the attachments installed on the chain, common configurations include roller chain conveyors, slat chain conveyors, pallet chain conveyors, and scraper chain conveyors.
For individual load handling, chains can be fitted with rollers, support plates, stops, or dedicated fixtures to carry cartons, pallets, and mechanical components. For bulk material conveying, scrapers or other attachments can push material along a trough.
Main features:
High load capacity: Suitable for heavy workpieces, pallets, and certain heavy-duty material handling applications.
Reliable power transmission: Chain engagement with sprockets provides positive power transmission, making chain conveyors suitable for continuous operation and applications requiring controlled positioning.
Flexible structural configurations: Different chains and load-bearing attachments can be selected according to the dimensions, weight, and movement requirements of the conveyed items.
Suitable for production line integration: Common applications include assembly lines, pallet conveying systems, warehouse logistics, and heavy-duty material transfer.
Chain conveyors require regular inspection of chains and sprockets. Long-term operation may cause chain elongation, sprocket wear, and increased transmission noise. The specific configuration should be selected according to the conveyed material or item. Not all chain conveyors should be classified as scraper conveyors.
Selection Considerations for Solid Material Conveying Systems
Each type of conveyor has its own operating range. Selection should not be based only on conveying capacity or equipment price. Material properties and site conditions also need to be considered.
Material properties
First, identify whether the material consists of powder, granules, lumps, or individual items. Check its bulk density, particle size distribution, moisture content, flowability, adhesion, abrasiveness, and temperature. Fragile materials require control of impact and shear forces. Sticky materials need special consideration for adhesion and blockage, while abrasive materials require suitable wear-resistant components.
Conveying route and installation space
Determine whether the material needs to move horizontally, at an inclination, or vertically. Confirm the conveying distance, lifting height, transfer points, and feed and discharge locations. Building height, floor space, and maintenance access also affect equipment selection.
Throughput and operating conditions
Determine the required hourly throughput, continuous operating time, start-stop frequency, and production cycle of upstream and downstream equipment. The actual capacity of each conveyor type must be calculated according to material properties and equipment specifications.
Environmental and safety requirements
For dusty, combustible, or explosive materials, consider equipment sealing, dust collection, grounding, and any necessary explosion protection measures. Food and pharmaceutical applications also require attention to contact materials, equipment cleaning, and cross-contamination control.
For projects involving uncertain material properties or special conveying requirements, conduct sample tests before purchasing the equipment. Testing helps verify actual throughput, material breakage, blockage risks, and cleaning requirements.
Custom Machining for Conveyor Components
Different types of solid material conveying equipment contain various metal structural and precision mechanical components, including conveyor rollers, drive shafts, bearing housings, motor mounting bases, sprocket mounting structures, screw shaft end components, support plates, and connecting flanges. Their dimensional accuracy, hole positions, materials, and assembly fits affect equipment installation and operating stability.
Hansheng Automation provides CNC precision machining of non-standard metal components according to customer-supplied engineering drawings. We support custom structural and mechanical parts for industrial conveying equipment and other automation systems.
In addition to conveyor components, we also undertake custom machining of precision yacht parts, RC racing car parts, tobacco packaging machinery components, and filling machinery parts.
